Question: Let \[f(x) =
\begin{cases}
2x + 9 &\text{if }x<-2, \\
5-2x&\text{if }x\ge -2.
\end{cases}
\]Find $f(-7).$
Answer: Because $-7<-2,$ we use the first case to determine that $f(-7) = 2(-7) + 9 = \boxed{-5}.$